Say ‘Cheese’: OpenSolaris’ Time Slider

“Introduced in November 2008 and updated in the most recent June
2009 OpenSolaris 2009.06 release, Time Slider is a graphical tool
that provides a window into the operating system’s powerful
snapshot feature. This enables a user to move a file or directory
back in time and watch how it changes. From there, it’s a simple
step to grab a version from out of the past and bring it back to
the present. All with just a couple of mouse clicks.

“To understand OpenSolaris’ snapshot feature you must know a
little bit about the operating system’s underlying ZFS file system.
Put simply, whenever a file is modified in ZFS, the original data
is left unchanged, and the modified data is written to a new part
of the storage pool. Since no data is actually deleted, the storage
pool contains all the data needed to create snapshots of the file
system, as it changes over time. Snapshots are taken automatically
by the file system or can be taken manually. They are very quick to
create because all the data required is already stored in various
places in the storage pool. And since all snapshots (and the
current files) share any common data, snapshots are space
efficient, or, put another way, you can usually keep large numbers
of snapshots without taking up too much storage space. The first
screenshot below, for example, shows a system with 12 snapshots
that take up a total of just 1.3MB of data.”

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